I like using the Pentax 110 50mm. I smuggle it into concert venues that don't allow cameras. It's so small that I can easily fit it in a pocket, and the body in another (without the lens). How else would I get a 50mm F2.8 in?

I also really like using a Nikon rangerfinder Nikkor 105mm F/2.5. It's a heavy beast. But it was a gift, and I get better results than my 40-150mm M.Zuiko (That lens really disappoints me, but it does seemingly weigh nothing after using the old Nikkor.)

Legacy glass is rarely superior in technical terms. But there's always something warm and natural about the results, so I like to use them when I have time to manual focus.